130 AR hybrid OTM BC

Gilly

On Target
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Feb 27, 2009
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Wondering what BC most are having luck with on this bullet with your favorite app? I have tried inputting data into 3 solvers and none match up with actual dope.

6.5 creedmore velocities measured on multiple occasions at 2920 average with lab radar. Weather data collected with kestrel for DA. When I try to calibrate or true app it moves velocity to 2990-3006 depending on range and solver I’m using. AB g7 and custom drag model both move it over 3000 fps. I have to move g7 bc way up like .31 range to make actual measured velocity work.

Any input or ideas on best way to run it? I’ve read plenty of info on app based solvers and short comings they have but well inside transonic range did not expect it to be this far off.
 

58blackflag

Sergeant
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May 30, 2012
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I’ve found BC to be less than advertised in both of my 6.5x47s but both run rather slower than what you are running. My current gun I’m using .285 G7.
Most important thing is that your corrections match actual hits so if your data is getting you hits, don’t sweat it too much.
 

Clearlight

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Jul 23, 2014
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I’m using AB with the CDM , and it’s within a click or 2 out to 1500 . Sounds
like you may have an issue with one of your inputs , scope height , tracking
etc etc .
 

Gilly

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I’m using AB with the CDM , and it’s within a click or 2 out to 1500 . Sounds
like you may have an issue with one of your inputs , scope height , tracking
etc etc .
Great advice it pays to check and double check. Scope height input had an error in it in AB profile. I never thought that number to be so sensitive but obviously it is. Now with correct number it is very close in AB, one other one not so much.

So with that in mind where is ideal place to measure? At turrets or near front of scope? With 20 moa rail there is a difference.
 

lte82

Shooter
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Mar 12, 2013
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Or just do some quick addition. Action diameter / 2 + base height + ring height.

Example 1: Remington diameter is 1.35", 20 moa base height is ..35" (measured at the center of the base or wherever your turrets sit above them), ring height of Badger med-high 34mm rings is 1.125" (base to center of rings).

Scope height from bore centerline is 1.35/2 + .35 + 1.125 = ~2.15".

Example 2, Integrated scope base: Action diameter 1.35", distance from bottom of action to top of pic rail 1.60", ring height 1.125".

Scope height is 1.35/2 + (1.60-1.35) + 1.125 = ~2.05"

A quick rule of thumb is ring height + 1" and you'll be very close on rem 700 based actions.
 

squib

Private
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Mar 10, 2012
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Curious if the issue has been resolved. I'm getting ready to try the AB custom curve myself.
 

Gilly

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Yes I had recently setup the profile and either didn’t get the last number in or it didn’t save I had .83 inches scope height error. 2.0 vs 2.83 actual and made a huge difference. This is on an AIAX, My 260 barrel profile was spot on with prime 130 which was why I was confused. Ended up with CDM and a calibration velocity 15-20 feet faster than my lab radar velocity. Hits out to 1100 last time out.
 

2wheels

Private
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Jan 31, 2018
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Or just do some quick addition. Action diameter / 2 + base height + ring height.

Example 1: Remington diameter is 1.35", 20 moa base height is ..35" (measured at the center of the base or wherever your turrets sit above them), ring height of Badger med-high 34mm rings is 1.125" (base to center of rings).

Scope height from bore centerline is 1.35/2 + .35 + 1.125 = ~2.15".

Example 2, Integrated scope base: Action diameter 1.35", distance from bottom of action to top of pic rail 1.60", ring height 1.125".

Scope height is 1.35/2 + (1.60-1.35) + 1.125 = ~2.05"

A quick rule of thumb is ring height + 1" and you'll be very close on rem 700 based actions.
Maybe I’m missing something? Shouldn’t the formula be one half of action diameter?